Immunohistological stains


Involves the process of selectively imaging protein antigens of a tissue section by exploiting the principle of antibodies binding specifically to antigens in biological tissues.

Immuno in reference to antibodies used in the procedure, and histo meaning tissue.

It is widely used in the diagnosis of abnormal cells such as those found in cancerous tumors.

Specific molecular markers are characteristic of cellular events such as proliferation or cell death.

Used to understand the distribution and localization of biomarkers and differentially expressed proteins in different parts of a biological tissue.

Visualising an antibody-antigen interaction can be achieved by antibody is conjugation to an enzyme, such as peroxidase, that can catalyse a color-producing reaction-immunoperoxidase staining.

The antibody can also be tagged to fluoresce in-immunofluorescence.

Immunohistochemistry requires proper tissue collection, fixation and sectioning.

The antibodies used for specific detection can be polyclonal or monoclonal.

Antibodies are classified as primary or secondary reagents.

The direct method of immunohistochemical staining uses one labelled antibody, which binds directly to the antigen being stained for, and the indirect method of immunohistochemical staining uses one antibody against the antigen being probed for, and a second, labelled, antibody against the first.

Both chromogenic and fluorescent dyes are available for IHC

Immunohistochemical staining is an excellent detection technique and has the advantage of being able to show exactly where a given protein is located within the tissue examined.

Hematoxylin: stains cell nuclei blue/black.

Eosin: stains protein and cell cytoplasm deep pink.

When used together, hematoxylin and eosin is termed ‘H&E.’

Periodic acid Schiff (PAS): for mucin and glycogen (purple).

PAS with diastase (PASD): digests glycogen and also detects mucin (pink/purple).

Alcian Blue (AB): stains mucin (blue)

Immunohistochemistry (IHC) relies upon the visual detection of a specific antibody that can adhere to a cell protein that is specific to a cell type or its cancerous counterpart.

Immunohistochemistry techniques have improved because more specific and reliable antibodies such as monoclonal antibodies and enzymatic labels are available.

IHC is used in combination with an analysis of lung tissue morphology on the H&E-stained tissue section.

Immunohistochemistry in lung histopathology has three roles: in diagnosis, in prognosis and identifying predictive’ markers for lung cancer therapy.

The technique is widely used in diagnostic surgical pathology for immunophenotyping tumors.

Many clinical laboratories have over 200 antibodies used as diagnostic, prognostic and predictive biomarkers.

BrdU: used to identify replicating cells.

Cytokeratins: used for identification of carcinomas but may also be expressed in some sarcomas.

CD15 and CD30 : used for Hodgkin’s disease

Alpha fetoprotein: for yolk sac tumors and hepatocellular carcinoma

CD117 (KIT): for gastrointestinal stromal tumors (GIST) and mast cell tumorsttf

CD10 (CALLA): for renal cell carcinoma and acute lymphoblastic leukemia

Prostate specific antigen (PSA): for prostate cancer.

Estrogens and progesterone receptor (ER & PR) staining are used both diagnostically as well as prognosis in breast cancer and predictive of response to therapy.

Identification of B-cell lymphomas using CD20

Identification of T-cell lymphomas using CD3.

TTF-1 is expressed in 83-100% of small cell lung carcinoma‘s, but is consistently negative in Merkel cell tumor.

CK7 associated with small cell lung cancer.

Melanoma is associated with S100.

Leukocyte common antigen is associated with lymphoma.

Immunohistochemistry can be used to assess which tumors are likely to respond to therapy, by detecting the presence or elevated levels of the molecular target: e.g. presence of hormone receptors can be used to determine if a tumor is potentially responsive to antihormonal therapy, and an intracellualar tyrosine kinase inhibitor, epidermal growth factor receptor (EGFR), and HER2/neu,

No tests are 100% specific.

Vimentin is present in almost all sarcomas and some carcinomas.

Desmin is contained in the tumor cells of muscle origin such as leiomyosarcoma or rhabdomyosarcoma.

S100 antigen is associated with tumors of neural sheath.

Immunohistologic PSA test can be positive for salivary gland carcinoma. Bold text

Leave a Reply

Your email address will not be published. Required fields are marked *